The automotive industry is moving aggressively in the direction of advanced active safety. Dedicated Short-Range Communication DSRC is a key enabling technology for the next generation of communication-based safety applications. Vehicle networks enable vehicles to communicate either with Road Side Units (RSU), in what is widely known as vehicle-to-infrastructure V2I communication, or among themselves, through vehicle-to-vehicle V2V communication. Wireless Access in Vehicular Environment WAVE is the core part of DSRC, which includes the suite of IEEE 1609.4 standards [1] family and IEEE 802.11p [2] that is built over IEEE 802.11 through amending many tweaks to guarantee and facilitate the provision of fast and reliable wireless access in vehicle networks. WAVE is the core part of DSRC; however, either of the two terms is commonly used arbitrarily. In some cases, the term DSRC is used as a more general term compared to WAVE.
As such, DSRC is currently considered the most promising wireless communication in vehicular network. However, DSRC must operate in rigorous and challenging environments which still require fast communication to maintain the connection with speeding vehicles at all times, strict Quality of Service QoS committed to predefined threshold delays for safety messages, minimal use of transmission power, and maintaining privacy and anonymity of roaming users etc.
Recent research in wireless vehicle networking has been focusing upon the heterogeneous integration of IEEE 802.11-based wireless ad-hoc networks with 3GPP cellular networks. Among the available technologies, the leading examples are the widely-deployed 3G/4G cellular networks and IEEE 802.11 based DSRC technology. 3G/4G technologies, such as UMTS or LTE, are predominantly used for wide-area wireless data and voice services via access to a base station BS/eNB. On the other hand, DSRC is used for short-range, high-speed communication among nearby vehicles and between vehicles and RSU. By integrating vehicular Ad Hoc network VANET with cellular, high data rate from IEEE 802.11P can be coupled with wide-range of communication. In the envisioned integrated network, if one vehicle is connected to the cellular network, it can serve as a gateway node for other vehicles in its vicinity to access the cellular network.
In most of the existing literature for vehicle communications, gateways (referred to RSU (Road Side Unit) sometimes) are considered static, deployed on the roadside at the fixed distance from each other, depending on their transmission range, which makes the overall system deployment costly. According to certain embodiments of the present invention as described in detail below, a mobile gateway refers to the dual-interfaced vehicle that relays the data from other vehicle sources to the LTE backhaul network. The dual interfaces are IEEE 802.11P and LTE. And this vehicle mobile gateway serves the vehicles in the cluster for the controlling signaling and forwarding the data under the assistance of the cellular network.
In the 3GPP scenario [3], the Machine Type Communication MTC Gateway device is a kind of MTC device that has 3GPP mobile communication capability. The devices located at the MTC capillary network do not have 3GPP mobile communication capability, i.e. they are local-access devices. They are connected to the MTC gateway device via local connectivity technologies such as IEEE 802.15, Zigbee, Bluetooth etc. Comparing with the above scenario, we can think that the vehicle mobile gateway as the MTC gateway device and local-access device as the vehicles with the IEEE 802.11P capability. And vehicle mobile gateway communicates with vehicles via local area interface (e.g. IEEE 802.11P); Vehicle mobile gateway communicates with the cellular network via LTE interfaces.
A prominent issue in the vehicle and cellular integrated networks revolves around the fast access and gateway management of the vehicular gateways.
For the integrated vehicle and cellular communications, most of the existing research focuses on the clustering, i.e., how to form the cluster and how to maintain/update the cluster during the movement. As the vehicle GW may need to report the central network on the safety applications, traffic management etc instantly, fast access to the cellular link for vehicle GW is another important issue for vehicle and cellular integrated communications which has not yet been studied in the literature.
Hence, there is still space for optimizing fast access and handover in terms of the RRC connection and handover procedure.